I just read some articles about how Germany 5G network works (5g NSA).
As Germany uses Inter-Site Anchoring is it possible that the GL X3000 just connect to the LTE and dont hoockup to the 5g network? anyone familar with this topic?
looks like there are many Problems with Gl X3000 in germany 
just found several older articles.
GL-X3000 Telekom Germany - #19 by SpitzAX3000
My Mobile Phone (Xiaomi Mi 11 Pro) uses Band 3 and Band 20 (NSA). So i tried to open only this two Band in my X-3000 but than it does not connect at all.
============Band Block / open ================
When i allow all 5G NSA Band but nothing else than it also does not connect.
looks like it only connect to LTE Band